DEVONSHIRE. 



G87 



Devon. Topsham, into an arm of the sea, which terminates at 

 ihire. Exmouth. The Tavy, the Plym, the Yealme, the 



— v — Arme, and the Avon, all rise in Dartmoor. The Tavy 

 falls into the Tamar, with which also the Plym unites 

 in forming Plymouth Sound ; the other three fall into 

 the British Channel within a few miles of. one ano- 

 ther. 



loads and The roads in Devonshire are, in general, remarkably 



anals. narrow, and by no means either well formed or well 



kept. Several canals have been projected in this coun- 

 ty, but few carried into execution. Among the former, 

 was one from Exeter to Crediton, and another from 

 Barnstaple to Topsham. By a survey taken with a 

 view to this last canal, it appeared that the low water 

 line at Topsham, is 2.5 feet higher than the low water 

 mark at the bridge of Barnstaple. A canal from the 

 quay at Exeter to Cooley bridge has been lately execu- 

 ted ; and one from Tavistock to the Tamar has been 

 completed for some time. 



if meralo- The mineralogy of Devonshire presents some appear- 

 ances worthy of notice. The chalk formation, which, 

 on setting out from London, and going in a direct line 

 from east to west, extends 1 50 miles, is lost on the 

 road to Axminster, within 4 miles of Honiton. On 

 leaving the chalk district, the transition country com- 

 mences, of which Exeter may be regarded as the centre. 

 Immediately after losing the chalk and flint, a red sand- 

 stone, with an argillo-ferruginous cement, succeeds. 

 About Honiton, it is in the state of coarse-grained gra- 

 vel ; and near Exeter it assumes the character of an are- 

 naceous sandstone. From Exeter, the red argillaceous 

 sand-stone continues for some miles on the road to Ply- 

 mouth. Near Chudleigh, it is succeeded by a vast 

 number of flint pebbles ; and between this place and 

 Ashburton, a blue compact limestone, with numerous 

 veins of calcai'eous spar, appeal's. In the neighbour- 

 hood of Ivy Bridge, the formation of the slaty and com- 

 pact grauwacke commences; but on the shore near 

 Plymouth, the cliffs are composed of limestone. The 

 transition limestone, however, in its true character, is 

 feund on the left bank of the Plym, at the eastern end 

 of the flying bridge. In ascending the valley of the 

 Arme, the point of termination between the grauwacke 

 and the granite is distinctly seen. The latter forms 

 the primitive rock of the mountain plain of Dartmoor 

 forest. It is a true granite, composed of felspar, 

 quartz, and mica. About three miles from Tavistock, 

 on the road from Twobridge, the grauwacke begins to 

 reappear, in a very distinct manner, at the height of 

 about 1129 feet above the level of the sea. Near the 

 place where the roads join from Plymouth to Oakhamp- 

 ton, and from Tavistock to Twobridge, a bed of green- 

 stone is found in the grauwacke slate ; the latter con- 

 tains more quartz, and becomes less slaty as we ap- 

 proach St Mary Tavy. The height of the line of su- 

 perposition of the secondary on the primitive rocks, 

 near Cullington, is 700 feet above the level of the sea ; 

 at Ivy Bridge hill, 631 feet; in the neigbourhood of 

 Harford Church, Dartmoor forest, 1129 feet; and in 

 the neighbourhood of St Mary Tavy, 648 feet. 

 Mines. Tin, lead, iron, and manganese, are found in Devon- 



shire, and also small quantities of gold, silver, copper, 

 bismuth, antimony, and cobalt. Formerly the tin 

 mines were abundant and profitable, now they are 

 scarcely worth the expence and trouble of working. 

 Lead ore is principally of a greyish blue colour. Some 

 rich veins of this metal were discovered at Combe Mar- 

 tin a few years since. They run nearly from east to 

 west, underlying towards the south ; they are worked 



with very little trouble or expenee, as they appear just 

 below the surface of the ground. The galena has 

 yielded from 20 to 168 ounces of silver per ton. Near 

 Combe Martin is also found a mine of iron. The princi- 

 pal vein is, in many places, two inches thick, and is said 

 to afford iron equal to that obtained in Wales, Consi- 

 derablequantitiesof bog iron are found in the Moorlands. 

 A mine of manganese was formerly wrought near Up- 

 ton Pyne, but it has been filled up and another opened 

 at Newton St Cyres. The matrix of the ore is the same 

 at both places. The soil is a deep red clay. The 

 deepest part of the mine is about 20 feet. The man- 

 ganese does not run in veins, but is found in flat, irre- 

 gular patches. From 150 to 200 tons are exported 

 annually, principally to London. Copper mines are 

 wrought at North Molton, in the parish of Brideston, 

 in the neighbourhood of Tavistock, and at Buckland 

 in the Moor. The mine near Tavistock, called Hawl- 

 friendship, though not more than 23 fathoms in depth, 

 has a rich vein of ore. The country round contains a 

 great quantity of killas ; and the matrix of the copper 

 is a caple. The direction of the mine is from east to 

 west ; and the inclination to the north, about 5 feet in 

 a fathom. The ore is generally sold in Cornwall, and 

 smelted in Wales. Antimony has been found in the 

 parishes of Chudleigh, Hennocke, and South Bovey ; 

 and cobalt, interspersed with filaments of silver, at 

 Sampford. 



Limestone is found in abundance in many parts of 

 Devonshire. In the eastern division of the county, it 

 is soft, like chalk ; but in the South Hams, and espe- 

 cially near South Molton, it is hard, with beautiful veins, 

 and admits of a fine polish, so as to be denominated 

 Devonshire marble. The finest kinds of Devonshire 

 marble, however, are found in the district of North 

 Devon. It has been lately much used, and a ware- 

 house opened in London for the sale of it. Gypsum is 

 found in a few places near Plymouth, united with lime- 

 stone ; and in other parts of the lime district, to the 

 south-west of Exeter. About three and a half miles 

 from Upper Pyrie, the extraordinary substance, called 

 Thorverton stone, is found. It is dug in a quarry to 

 the depth of 40 feet, and is compact in proportion to its 

 depth. There are three or four quarries all in the same 

 rocks ; a calcareous amygdaloid, the nature of which 

 varies considerably. One part of the stratum exhibits 

 an appearance extremely like toadstone. The granules 

 are partly calcareous, partly argillaceous, and partly 

 steatitical. In some places, the nodules are small, in 

 others about the size of a pea. Some parts of the quar- 

 ry have the appearance of porphyry, others are of a 

 blackish colour, while others are intersected with nar- 

 row veins of white calcareous earth. A substance 

 somewhat similar to Thorverton stone is dug out of 

 Heavitree quarry near Exeter, but it is more coarse and 

 loose textured, and approaches nearer to the nature of 

 a breccia ; the strata in this quarry are from six to eight 

 feet in thickness, and dip south-east at an angle of about 

 1 5°. The stone dug from this quarry, hardens more 

 and more by exposure to the air. The gates and walls, 

 and most of the ancient edifices in Exeter, have been 

 built of Heavitree stone ; it is used for coarse millstones 

 for sheelrng clover; A kind of slate, called Holland 

 blues, is got near East Alwington ; and some good co- 

 vering slates have been found at Lewtrenchard and 

 Werrington. The Black-down hills afford a soft species 

 of sandstone, which is converted into whetstones. A 

 considerable quantity of brown potters clay is raised in 

 the parish of Fremington, and conveyed to Barnstaple 



Mineralo- 



